Background on Bancroft Visor Models (?)

I've been searching for some additional information on Bancroft's visor models - while there's plenty out there about the "Flighter," and I've found references to "The Wales" as the high end offering, does anyone know more detail about how the "Zephyr" fit into the model range?

It appears from a quick glance that the Zephyr had a longer life as a peaked/visor offering.

Thanks!